Keeps track of unsuccessful authentication attempts via an int counter
in the state struct. Displays on the unlock indicator, but will be
replaced by the Caps Lock text if enabled.
This implements customization for the indicator as proposed in sway#2788 with comments from sway#3367 in mind.
The default behaviour does not change exept for the caps lock text color.
Since these changes seem to be lost in the split I've remade them.
